A rare celestial event, the passing of a comet, results in a catastrophic happening on Earth. Those who watched the event are turned to dust, and the few who somehow avoided looking at the sky are spared. Society crumbles overnight, leaving the empty streets littered with the clothing and remnants of the unfortunate. Among the survivors are two sisters, Regina and Samantha, who emerge from the safety of their steel-lined enclosures to find a deserted Los Angeles. They discover that they are some of the very few who are still alive, and as they grapple with the terrifying realization of the widespread death, they must also adapt to a new post-apocalyptic existence.

Navigating through the desolate city, the sisters encounter other survivors, including Hector, a man with whom Regina forms an attachment. However, they soon realize they are not alone in another sense: mutated creatures roam the shadows, remnants of humans turned violent and animalistic by the cosmic event. As they try to maintain some semblance of normalcy amidst this nightmare, they come across a secret group of scientists operating out of a think tank who may not be the saviors they appear to be. Trust becomes a scarce commodity as the sisters learn more about the changed world and the dangers that lurk around every corner.